This ignores the very real problem that chronic homeless people tend to suffer from mental illness problems and you'd need to ensure they are clean 24/7. There would also be the issue of people using them for drugs and what not.

This also ignores that the solution you propose has already been tried in other cities and hasn't worked out. Which could be part of the reason why you received such a harsh response.

The solution wouldn't be portable toilets, it would be fully fledged bathroom units available to the homeless with options to shower, shave, fresh clothing etc. Of course a better and longer lasting solution would be actual housing for the homeless but that seems to be a harder sell for some people.